Syringe.



J. PAYNE.

SYRINGB.

APPLICATION FILED 0GT.14, 1910. J*044,688*D Patented Nov. 19, 1912.

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Specication of Letters Patent.

Patented N ov. 19,1912.

Application filed October 14, 1910. Serial No. 587,046.

To all whom t may. concern Be it known that l, JOSEPH PAYNE, of Belmont,in the county of Middlesex and State of Massachusetts, have inventedcertain new and useful Improvements in Syringes, of which the followingis a specification. 4

This invention relates chiefly to hypodermic syringes used by dentistsand other practitioners.

The syringeincludes a barrel, to the outlet of which a hypodermicvneedle1s connected, and a piston movable in the barrel and adapted to ejectfluid through the needle.

The invention has for its object, first, to provide improved means forpacking the piston and preventing leakage of the fluid between it andthe rear end of the barrel.

The invention consists in the improvements which I will now proceed todescribe and claim.

Of the accompanying drawings-Figure 1 represents a side view of asyringe to which my improved packing is applicable. Fig. 2 represents asection on line 2-2 of F1g. 1. Fig. 3 represents a section on line 3 3of Fig. 1. Figs. 4 and 5 represent, respectively, a side and end view ofthe piston 'packlng embodying my invention, removed from the barrel.Fig. 6 represents' a section on line 6 6 of Fig. 5.

In the drawings, 12 represents a syringe barrel of cylindrical form,having an outlet at its forward end, and means such as a screw-threadednipple 13 through which the outlet extends, for the engagement with thebarrel of the base 14 of a hypodermic needle 15, said base beingexternally formed as a nut so that the needle can be screwed on or off.16 represents an external screw thread formed on the periphery of thebarrel near its rear end. The periphery of the barrel is reduced betweenthe screw thread 16 and the rear end or extremity of the barrel, to forma smooth surfaced cylindrical portion 17 of smaller diameter than thescrew thread, said portion constituting a guide for the packing casehereinafter described.

18 represents a piston which is movable ,in the barrel and is adapted toeject fluid from the barrel through the outlet, said piston, as hereshown, being provided with a head 19 formed to bear upon the palm of theoperators hand and hereinafter referred to as a palm-rest.

20 represents a hollow cylindrical packing case which is composed of acylindrical shell of thin sheet metal formed internally to have asliding t on the guide 17, and provided at its rear end with an inwardlyprojecting flange 21 which partially obstructs said end and forms anopening for the piston 18. The opposite end of the case is open orunobstructed.

22 represents a cylindrical packing sleeve of compressible material suchas leather, rubber or any suitable packing composition adapted to beinserted in the unobstructed end of the case and to form a tight jointaround the piston 18, said sleeve forming an opening which is acontinuation of the opening formed by the flange 21. Said sleeve isformed to enter and closely fit the interior of the case 20 and toclosely fit the periphery of the piston 18, the packing sleeve beingshorter than the case and bearing at one end against the flange 21, sothat the opposite end of the case, projects forwardly from the sleevesufliciently to engage and slide on the guide 17.

23 represents a packing nut which has at one of its end portions aninternal screw thread formed to engage the external thread 16 on thebarrel 12, the oppo-site end of the nut being provided with an inwardlyprojecting flange 24 which bears on the rear end of the packing case 20.The portion of the nut between the flange 24 and the internal screwthread of the nut is formed to inclose the packing case 20.

When the packing is first applied to the syringe, the length of thepacking sleeve 22 is such that when it bears on the rear end of thebarrel, as shown by Fig. 2, the portion of the sleeve that projects overthe guide 17 is separated from the shoulder 25 at the outer end of saidguide, by a space of considerable width, so that there is room foraconsiderable forward movement of the packing case 20'. on the guide, anda corresponding compression of the packing sleeve 22. It will bel seentherefore, that the packing may be adjusted from time to time tocompensate for Wear, by turning the nut 23 forward, and thus causing thepacking case to slide forward and compress the packing sleeve, thusincreasing its pressure on .the piston. The packing -sleeve 22 isseparated from the nut 23 by the packing case so that there is nofrictional contact between the nut and packing sleeve, the sleeve beingtherefore adapted to be readily compressed on the piston. The packing,composed of the sheet metal case 2O and the compressible packingv sleeve22, may be put upon the market as an article of manufacture, a number ofsaid packings being supplied with each syringe, so that the user mayreadily renew the packing by'discarding one of which the packing sleevehas been rendered useless and substituting another packing in its placewithout the necessity of touching the packing sleeve itself. y

26 represents a rest for two lingers of the hand which manipulates thesyringe, said rest being arranged to aord a bearing for the lingerswhile the palm-rest bears against the palm of the same hand. rifhefinger rest is composed of a strip or plate having an enlarged centralpo-rtion containing an orifice 27 adapted to receive the barrel 12, andcurved end portions or wings constituting the finger bearings andprojecting from the opposite sides of the barrel. rllhe finger rest isremovable from the barrel, and when in place on the barrel bears againstthe abutment 28 located between the ends of the barrel and rigidlysecured thereto, said abutment being preferablyn ring or collar attachedto the barrel in any suitable way, or if desired, formed integraltherewith. The finger rest 26 bears on the side -of the abutment nearestthe needle 15, so that pressure of the operators fingers on the resttends to force it against the abutment. Rotation of the finger rest onthe barrel is prevented by ears 29 formed on the barrel and recesses 30formed in the finger rest to receive said ears, as shown by Fig. 3, thesaid ears and recesses constituting complemental members vforinterlocking the linger rest with the barrel.

31 represents a set screw engaged with a tapped socket in the fingerrest and adapted to bear on the barrel to vprevent separation of thenger rest from the abutment 28. When the finger rest is removed from thebarrel, it may be utilized as a wrench for applying and removing theneedle 15, the finger rest being provided with wrench sockets 32 at itsends, each of which is formed to engage the nut 14 constituting the baseof the needle. It is obvious that one wrench socket, instead of two, maybe provided if desired.

l claim The combination with an externally threaded tubular memberhaving a smoothsurfaced cylindrical portion of lesser diame- /ter beyondthe threaded portion, of an internally threaded nut, a packingcomprising a hollow cylindrical case adapted to be inserted in said nutand having at one end an inwardly projecting annular ange partiallyobstructing said end and forming an opening adapted to receive a rod,the opposite end of the case being unobstructed, and a compressiblecylindrical packing sleeve fitting the interior of the case and forminga continuation of the opening in the annular flange, said sleeve bearingat one end against the iiange and being shorter than the case so thatits opposite end is within the open end of the case, whereby the packingas a whole may be handled without contact of the fingers with thepacking sleeve, the open end portion of the case projecting outwardlyfrom the packing and forming a recess to receive the smooth surfacedportion of said tubular member. v

In testimony whereof l have aiiiXed my signature, in presence of twowitnesses.

JOSEPH PAYNE. Witnesses:

C. F. BROWN, R W. lnzzn'r'rr.

